Compressor



April 1, 1941. HERZMARK 2,236,853

cordrnnsson 29, 1959 a She ts-Sheet 1 Filed April 1, 1941. HERZMARK 2,236,853

coiarnnsson File d May 29, 1959' s Sheets-Sheet s Patented Apr. 1, 1941 COMPRESSOR.

Nicolas Herzmark, Paris, France Application May 29, 1939, Serial No. 276,462 In Great Britain May 28, 1938 (Granted under the provisions of sec. 14, act of March 2, 1927; 357 0. G.

4 Claims.

two pistons connected together by means of aslotted crosshead reciprocating between vertical guides in the casing and having a sliding-die engagement with the crankshaft.

Another object is to provide for inter-stage cooling of the compressed air or gas by means of externally cooled passages formed in the engine casing and extending between shallow circular or annular spaces above and below the top and bottom ends of the cylinders.

A further object is to provide for interrupting the operation of the compressor when the air or gas pressure reaches a desired limit.-

Other objects of the invention will appear from the subsequent description given with reference to the accompanying drawings, in which- Fig. 1 is a sectional elevation of a preferred embodiment of the improved compressor.

Fig. 2 is a plan view in section on the broken line 2-2-2 of Fig. 1.

Fig. 3 is a part sectional elevation, viewed at right angles to Fig. 1, and showing a cut-out device in transverse section.

Fig. 4 is a sectional elevation of the cut-out device, viewed at right angles to Fig. 3.

Figs. 5, 6 and 7 are details of the cut-out device.

As shown in Figs. 1 and 2, the compressor has its low-pressure cylinder ll arranged above and the high-pressure cylinder l2 below the crankshaft I3, the two pistons l4, l5 being of the trunk type and connected together by means of a slotted crosshead I 6 reciprocating between vertical guides l1, l8 and having engagement with the rotating crank l3 by means of a sliding die l9. The crankshaft is rotatablymounted in bearings 20, 2|, preferably of ball or roller type carried by the end plates 22, 23 which are bolted to the open sides of the block or casing 24; one of the end plates is provided with a stufiing box 25 through which the crankshaft projects for connection to the drive.

The two cylinders ll, l2 are formed'by liners pressed into cavities 26, 21 at the top and bottom ends of the block or casing 24, the latter being a casting of light alloy and the cavities being themselves lined by barrels 28, 29 cast in the block; these barrels are shouldered at 30, 3lto. engage the block and the liners respectively. The upper cavity 26, which receives the lowpressure .cylinder'or line'r H, is in communication with the atmosphere by way of a port 32 at one side, air being allowed to enter the cylinder from this cavity through ports 33 cut in the cylinder or liner II at aposition corresponding to the bottom end of the piston stroke; the lower cavity 21, which receives the high-pressure cylinder or liner 12 within its barrel 29, is adapted to provide a sump for oil lubricating the work ng parts and serving to cool the highpressure cylinder. The cross-head guides l1, l3, consisting of part-cylindrical shells, are also cast in the engine block. one on each side of the central openings for the crankshaft [3, the guides being secured in place by studs or rivets 34, as indicated in Fig. 2.

Interstage communication between the two cylinders H, I 2 is provided by tubes 35 cast in the block 24, these tubes beingpreferably arranged in pairs adjacent to the cross-head guides l1, Is, to which they are secured by brazing before being inserted in the mould for casting the block. 'In the operation of the compressor, the tubes 35 are efficiently cooled at the exposed side surfaces of the block which are shown provided with horizontal cooling fins 36; as seen in Fig. 1, these tubes are approximately vertical for a height corresponding to the space within which the crosshead l6 moves but their ends are inclined inwardly towards the vertical axis of the cylinders inside the walls of the two cavities 26, 21, so as to connect with shallow circular or annular spaces v31, 38 respectively above and below the top and bottom ends of the cylinder liners. The lower ends of the tubes are preferably curved inwards towards the axis, so as to pass radially through the barrel 29; all the tubes may be brazed or otherwise connected to the cylinder barrels 29, 29, prior to insertion in the mould.

The liners H, l2 are,held in position in the barrels by cylinder heads 39. 40 screwed into the ends of the barrels. The low-pressure cylinder head 39 is formed with a circular recess 4| on its' lower face. the edge of this recess being chamfered at 42 to engage the bevelled edge 43 of a valve plate 44 secured by a central screw 45 to a cover plate which rests uponthe top end of the liner H; within theshallow annular type, made for example of bronze about 0.4 m/m. thick. Holes 49 in the cover plate 46 are normally sealed by this valve disc, but upon the rise of the piston l4 the pressure in the cylinder ll lifts the valve from its seating so that the air can pass by way of radial ports 58 to holes 5! in the valve plate 44; these holes, which are approximately in line with the holes 49, communicate with the recess 4| of the cylinder head, and by way of a central opening 52 in the latter with the space 31 leading to the tubes 35, a cap nut 53 being screwed upon the exterior of the barrel 26 to enclose the space 31.

The high-pressure cylinder head 48,-screwed into the barrel 29, carries two disc valves, one 54 of annular shape controlling the transfer of air from the annular space 36 fed by the tubes 35into the high-pressure cylinder, and the other 55 of circular shape to control the delivery of high-pressure air. The annular valve 54 is mounted in a recessed valve plate 56 bearing against the bottom end of the liner l2, and this valve rests normally upon a' cover plate 51; aligned 'holes 58, 59 in the two plates 56, 51, and radial ports 66 in the recessed portion of the valve'plate 56, allow the air to pass upwards into the cylinderwhen the valve lifts upon the upward movement of the piston l5. The holes 59 in the cover plate 51 communicate with the annular space 38 by way of a-circular trough 6| formed in thecylinder head 40 and radial holes 62 through the outer wall of this trough.

The valve plate 56 has a tubular boss 63 extending downwards through the cover plate 51 and cylinder head 46, within which boss the delivery valve 55 is located; the valve rests normally against a perforated seating 64, being held up by a coiled spring 65 surrounding the shouldered and perforated extremity of a hollowplug 66 screwed into the boss 63. When the valve 55 lifts under the pressure of air in the high-pressure cylinder, the air passes through the perforated sides and along the bore of the plug 66 into the space 61 within the lower end of they barrel' 29, which is closed by a screw-threaded space 41 between the plates '44, 46, there is mounted a delivery valve 48 of the annular disc end of this fitting allow the air pressure within the delivery pipe 11 to pass into two ducts 83, 84,

formed in the cut-out body 16 and extending to the outer ends of a pair of small cylinders 65, 66 of slightly different diameter; these cylinders may be 'of diameters of, 10 m/m. and 11 m/m. respectively, and their ends are closed by screw plugs 61, Two pistons 88, 89 working within the cylinders are connected together by a .piston rod 98 having rack-teeth 9| formed along the central portion of its length; the smaller piston 89 is engaged by a spring 92, the force of which is just suflicient to prevent movement of the two pistons when both 'are subjected to the same pressure, until that pressure reaches the limit set for the delivery, whereupon the spring yields and allows the pistons to move towards the right hand side of Fig. 4; 3

The rack teeth 9lengage with a partly toothed wheel 93 secured upon a spindle 94 mounted in the body 16; the upper half of this wheel is formed with hexagonal faces 95, upon one of which there rests a spring plunger 96 mounted in the top of the body, the plunger acting to ensure a snap-movement of the wheel when actuated in either direction by the piston rod 90. The spindle 94 also carries a segmental valve-plate or shutter 91 having a port 96 and resting against a flat facing 99 in which there is formed a port I06;

the port 98 is adapted to register with the port I80 in one position of the spindle 94, viz. when the delivery air pressure has caused the pistons livery pipe 11 although having access to the cylplug 66. The cylinder head! is provided with a packing ring 69, compressed by a ring nut III, to

prevent leakage of the high-pressureair along the screw-threads of the cylinder head and thus back into the trough 6| which contains air at lower pressure;

The airleaves the space 61 by way of aligned holes H, 12 in the barrel 29and casing 24, these holes leading into a port I3 in a cut-out device or safety blow-off shown ,in sectional views in Figs. 3 and .4. From the port 13 there extends a vertical passage 15 controlled by a non-return'valve16'of disc type, leading to a delivery pipe 11 connected to the air receiver or "bottle (not shown). In order to interrupt the operation of the compressor when the delivery pressure reaches the desired limit, the cut-out device'is arranged to open a passage for the escape of the high-pres sure air to the atmosphere, without 'however allowingdischarge of air back from the delivery I pipe 11. The-cut-out device comprises a body 16 bolted .to the side of the casing 24 beneath the stuffing box 25; the port 13 is formed in the face valve 16 and its spring 6|. Holes 82 in the inner inders 65, 66 byway of the ducts 83, 84, cannot so escape. As soon as the delivery pipe pressure falls, due for example to consumption of air for starting anengine, the pistons 66, 69 return to dially from the outer periphery and along concentric but interrupted arcs intersecting or meeting the radial slits, so as to ensure uniform seating. In this and other respects, the design and material employed may be such as the judgment of the manufacturer dictates.

' I claim:

1. A twostage compressor, comprising highpressure and low-pressure cylinders, pistons reciprocating in said cylinders, a crankshaft, a crosshead engaged by said crankshaft and connected to said'pistons, guides for said crosshead,

interstage communication passages between the outer ends of said cylinders, valve-fitted cylinder heads secured at the opposite ends of said cylinders, a delivery passage from said high-pressure cylinder, and a cut-off device including piston mechanism controlling an escape from said delivery passage' and a latching device tending to hold said piston mechanism-in one or other of its extreme'positions- 4 .2. A two-stage compressor, comprising highpressure and low-pressure cylinders, pistons reciprocating in said cylinders, a crankshaft, a crosshead engaged by said crankshaft and connected to said pistons, guides for said crosshead, interstage communication passages between the outer ends of said cylinders, valve-fitted cylinder heads secured at the opposite ends of said cylinders, a delivery passage from said high-pressure cylinder, and a cut-off device controlling an escape from said delivery passage, said 'cut-ofi device including two aligned cylinders of slightly diflerent diameter, a pair' of connected pistons reciprocable in said cylinders and both subjected to the pressure of air from said highpressure cylinder, a shutter operated by said connected pistons and normallyclosing said escape from said delivery passage, and means for delaying the operation of said shutter by said pistons upon variation of said pressure,

3. A two-stage compressor, comprising highpresure and low-pressure cylinders, pistons reciprocating in said cylinders, a crankshaft, a crosshead engaged by said crankshaft and connected to said pistons, guides for said crosshead, interstage communication passages between the outer ends of said cylinders, valve-fitted cylinder heads secured at the opposite ends of said cylinders, a delivery passage from said high-pressure cylinder, and a cut-off device controlling an escape from said delivery passage, said cut-ofi device including piston mechanism operated by the pressure of air from said high-pressure cylinder and means for delaying the action of said cutoff device upon variation of said pressure.

4. A two-stage compressor, comprising highpressure and low-pressure cylinders, pistons reciprocating inv said cylinders, a crankshaft, a crosshead engaged by'said crankshaft and connected to said pistons, guides for said crosshead, interstage communication passages between the outer ends of said cylinders, valve-fitted cylinder heads secured at the opposite ends of said cylinders, a delivery passage from said high-pressure cylinder, and a cut-off device controlling the operation of said compressor, said cut-off device including piston mechanism operated by the pressure of air from said high-pressure cylinder and means for delaying the action of said cut-oil device upon variation of said pressure.

NICOLAS HERZMARK. 

